Olin Lathrop wrote: > James Newton, webhost wrote: > > A circuit with two inputs and one output. > > > > All I/O optical in the human visible light range. > > > > All I/O in pulses of light of a width and frequency range discernable > > by the human eye. (0 to 20 Hz) > > > > The output frequency varies over the range in inverse proportion to > > the mathematical product of the input frequencies with an acceptable > > error of 10 percent. > > > > Optimize the design for low cost of production by assembly workers > > who have little technical ability. > > Now I think we've got something to work with. By the way, this is very > different from anything you said before. This is the first time we are > learning that the output frequency should be the *product* of the two input > frequencies. So to write your spec more formally: > > Fmax = maximum input and output frequency (20Hz) > F1 = input frequency 1 > F2 = input frequency 2 > Fo = output frequency > > F1 * F2 > Fo = ------- > Fmax I haven't been following this thread very closely; my mind is still trying to imagine the application for a cheap fuzzy-logic human-readable optical NAND gate. As a teaching tool, I would think it would be hopelessly confusing, and how are you going to prevent stray feedback paths? However, I don't think the equation matches the description above. For one thing, it fails all of the limit cases (F1, F2 = 0, F1, F2 = Fmax). I think you meant: F1 * F2 Fo = Fmax - ------- Fmax Converting to period: 1 1 -- * -- 1 1 P1 P2 -- = ---- - ------- Po Pmin 1 ---- Pmin or P1 * P2 * Pmin Po = ---------------- P1 * P2 - Pmin^2 > One wrinkle to deal with is infinite periods. "An acceptable error of 10%" can be interpreted several ways, but one obvious way is that any input or output frequency can be considered to be Fmax when it gets to 0.90 * Fmax, or 18 Hz. This means that the minimum input or output frequency that needs to be different from zero is on the order of 2 Hz. > You still have to do some analog, however. ... and some mechanical design, especially related to getting the signals in and out correctly. And you need to work out how these gates are going to be powered, etc. My brain hurts. so I'm going to quit now. -- Dave Tweed -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu